1. Field of the Invention
The present invention relates to air conditioning systems, and more particularly, to a compact air cycle air conditioner that utilizes the area to be cooled as a heat or cold storage chamber.
2. Description of the Related Art
Air cycle air conditioners have been proposed for some years as an alternative to vapor-compression air conditioners in residential, commercial and automobile applications, see for example, U.S. Pat. Nos. 5,121,610 and 5,295,370. This is because they have several advantages over vapor-compression systems. Firstly, because the evaporators of vapor-compression heat pump devices operate at or near 0xc2x0 C., their heating capacity is seriously impaired at low ambient temperatures, since they rely on heat transfer from ambient to the evaporator. Secondly, in cold weather ice forms on the evaporator heat transfer surfaces thereby increasing pressure losses and also reducing evaporator effectiveness. Thirdly, vapor-compression devices use chlorofluorocarbons (CFCs) as the refrigerant which presents manufacturing and maintenance problems with regard to refrigerant leakage, problems which are substantially reduced when air is used as the refrigerant. In addition, CFCs are known to have a harmful effect on the Earth""s ozone layer and it is thought that they may also be contributing to global warming caused by the so-called greenhouse effect.
Despite these advantages, air cycle air conditioning systems have yet to make a significant impact on the residential, telecommunications and more particularly the automobile markets. This can be attributed to the fact that air cycle designs have been previously based on regenerative heat exchangers for improving the coefficient of performance (COP). However, the improvement is minimal when the increased losses due to the presence of the heat exchanger(s) are taken into account, and may also be seen as expendable when offset against the attendant increases in complexity, size and cost of the conditioning system.
For purposes of automobile and telecommunication applications, these prior art air conditioning systems have proven to be too large and or not sufficient. For systems utilizing CFCs, a condenser is required and placed in front of the automobile radiator. This increases the heat load for the entire cooling system of the engine. In addition, when Freon or other CFCs are used, these systems generally come with high maintenance costs. When using a straight air cycle air conditioning system that generally consists of a compressor, air to air or air to water heat exchanger and a cooling turbine, the advantage is that they are generally compact in nature and low in maintenance costs. However, similar to the CFC systems, the heat exchanger is disposed in front of the automobile radiator which inherently prevents the heat exchanger from enabling a reduction in the temperature of the compressed air below that of the outside air. Thus, in order to reach and air temperature close to 0xc2x0 C. after the turbine, higher pressure is required in the compressor. This higher pressure requirement required significantly more power which takes away from the engine power provided to the automobile. In addition, since the air from the turbine is generally fed directly into the automobile cabin space, there is a high noise level associated with such systems.
In telecommunication systems, the size of the air conditioning unit is significant part of design considerations for rack and cabinet type systems. Therefore, an air cycle air conditioning system that operates efficiently and can be made small enough to fit within or on a telecommunications rack cabinet without consuming a large amount of valuable space would be desirable.
In addition, if for example you have air with 30xc2x0 C. and 60% humidity, in order to cool this air from 30xc2x0 C. to 0xc2x0 C. requires approximately twice the amount of energy than otherwise required to cool dry 30xc2x0 C. air to 0xc2x0 C.
It is therefore an object of the invention to provide a more compact and efficient air cycle air conditioning system.
It is another object of the invention to provide a more compact and efficient air cycle air conditioning system that can be specifically integrated into automobiles by using the automobile cabin as a heat or cold storage chamber and thereby eliminate the need for a heat exchanger disposed in front of the car radiator.
This and other objects are achieved in accordance with an embodiment of the present invention in which the air cycle air conditioning system includes a compartment to be cooled that is adapted to operate as a primary heat or cold storage chamber within the system. A cooling turbine is connected to the heat or cold storage compartment and serves to expand the air received from the compartment. A main heat exchanger receives the expanded air from the cooling turbine and in conjunction with a fan, is used to blow the cooled air within the main heat exchanger into the compartment. A main compressor is operable to compress the expanded air prior to exhausting it from the system, and as such can be utilized like a turbo charger for the engine. In this manner, the compressors can be used to power the air cycle air conditioning system, and the exhaust from the compressors can be used to work in conjunction with a turbo charger for the car engine.
In other embodiments, a desiccant is added to remove moisture from the ambient air blown into the system and additional valves can be added to enable the operation of the air cycle system as both and air conditioner and a heat pump.
Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein.